An improvement in power efficiency is beneficial to transmission devices of wireless communication systems because miniaturization and energy conservation are advancing in the transmission devices.
As an example of improving power efficiency of the power amplifier, there is a drain or gate voltage control technique for realizing highly efficient amplification by controlling a voltage applied to a drain or gate electrode as described in Japanese Laid-open Patent Publication No. 2008-22513. For this highly efficient amplification, timings of a signal input to the power amplifier and a voltage control signal may be matched for obtaining a predetermined output in the drain or gate voltage control technique.